When popular Ruben Plotnick invites himself over, David is particularly worried about how this class clown will react to Grandma Rosie and her unpredictable behaviour. But the visit turns out to be a great success and a revelation to David, who learns something about Ruben and more about himself.

When the coolest kid in the class drops by David's house after school, David is worried about how popular, zany Ruben Plotnick will react upon meeting unpredictable Grandma Rosie." Will he make fun of her to his classmates? Will he imitate her whispery voice? What will he do if Grandma Rosie suddenly wants to dance?" To his surprise, and relief, David learns that although Ruben may be a joker, he has an instant rapport with Grandma Rosie and accepts her odd behavior. In fact, when Grandma Rosie calls out, "Nate, let's waltz!" Ruben gallantly and proudly dances around the kitchen with her. This heartwarming story of senility and school-age embarrassment reveals the importance of looking beneath the surface to really get to know someone. By accepting Grandma with all of her quirks, Ruben shows that he has a warm heart and can be a true friend.